Latest news with #microbiologists
Medscape
3 days ago
- Health
- Medscape
Little-Known Gut Nutrient Is Emerging Player in Cancer Fight
An under-the-radar micronutrient is having a moment. Queuosine — just call it 'Q' — is a molecule that humans can only get from foods and gut bacteria. It's has been known to microbiologists for decades, who know it plays a role in protein synthesis — as well as cancer growth, brain health, and inflammation. Yet, it hasn't been clear how Q moves from the gut into cells throughout the body. Now the curtain has been pulled back. The authors of a study published in Proceedings of the National Academy of Sciences ( PNAS ) have pinpointed a gene ( SLC35F2 ) that helps transport Q to cells. The researchers say the new finding could help scientists figure out how to use the micronutrient to fight disease. 'It's 70 years ago now that Q was discovered,' said study author Vincent P. Kelly, PhD, Professor of Biochemistry in the School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland. 'What's exciting about this study is the fact that we never understood how we actually took that molecule from bacteria in our body and transported it into our cells, and this explains how we do it.' Q: A Brief Primer The PNAS study looked at both queuine (q), a modified nucleobase, and its nucleoside Q. A quick refresher: A nucleobase is a nitrogen-containing molecule that is one of the building blocks of DNA and RNA. And a nucleoside is a molecule made of sugar (either ribose or deoxyribose) plus a nitrogenous base (purine or pyrimidine) — also a building block of DNA. All of the cells in the human body are eukaryotes — they have a nucleus — and they rely on the micronutrients Q and q, which lurk in the human gut. They come from gut bacteria or a person's diet (most commonly meat, eggs, dairy, fruits and vegetables, and fermented foods), said Kelly. Prior studies had given hints that cellular uptake of Q and q is mediated by a selective transporter, but Kelly said that this transporter's identity 'remained elusive' until now. 'Almost all eukaryotes take the Q molecule and incorporate it into the transfer RNA (tRNA) in the body,' said Kelly. 'tRNA is critical for making protein. It's essential — essential for everything,' he said, pointing out that the average adult human is composed of about 12 kilograms (26 pounds) of protein. How does Q get into gut bacteria and the food we eat? The Q molecule is more or less everywhere, Kelly said. 'It's in the oceans, it's in the soil. Plants, which are eukaryotic, take it from the soil. And yet, very little is known about it. I'm surprised more people aren't knowledgeable about it,' he said, especially considering public interest over the years in health-oriented micronutrients like vitamins and 'macros' like carbohydrates, fats, and proteins. What They Found, What It Means Collaborating with researchers from Germany, Northern Ireland, the United States, and his own colleagues in Ireland, Kelly said they used a cross-species bioinformatic search and genetic validation — research techniques that enable scientists to analyze vast amounts of genomic data from across different species — to determine that Q and q are 'salvaged' from the gut by SLC35F2 and ferried to different tissues throughout the body. 'There's a whole biology built around this micronutrient,' said Kelly. Cracking the identity of the transporter of Q and q opens up opportunities for important research, Kelly said. It will lead to a deeper understanding of how intracellular levels of both micronutrients are regulated and how their deficiency is associated with diseases. The study findings 'represent an important leap in our understanding of queuosine biology. Queuosine is a unique tRNA modification to its precursor, queuine, which is not synthesized de novo in mammalian cells,' said Sherif Rashad, MD, PhD, Associate Professor in the Graduate School of Biomedical Engineering and the Graduate School of Medicine at Tohoku University in Sendai, Japan. Rashad said scientists' understanding of how q is imported into cells was 'virtually nonexistent' until now and that the authors of the PNAS study used 'an elegant but grounded approach' to identify the first q importer. The finding 'paves the way for new discoveries in the many fields at the crossroads of queuosine biology,' he said. Zdeněk Paris, PhD, Head of Laboratory, in the Laboratory of RNA Biology of Protists, at the Institute of Parasitology in Ceske Budejovice, Czech Republic, agreed. 'This study advances the field of queuosine research by identifying the primary transporter and establishing a direct link between the function of SLC35F2, intracellular queuosine levels, and vital cellular processes, which can explain how a deficiency of Q and/or its free base, queuine (q), contributes to various conditions, including neurological disorders and cancer.' Paris said, 'Prior to this study, no specific transporters for the intracellular uptake of Q or q had been identified in any eukaryote.' He said the research is 'high-quality.' He pointed out that the researchers also demonstrated that SLC35F2 is the sole high-affinity plasma membrane transporter for the Q nucleoside and the primary high-affinity transporter for the nucleobase q in human cells. 'Its high expression in the human alimentary canal strongly suggests a critical role in Q/q uptake from the gut during digestion,' he said. 'This reveals how these micronutrients, which are synthesized exclusively by bacteria, are salvaged from the gut microbiome and/or diet and delivered to various body tissues. Based on the obtained data, the authors propose a model in which Q is transported from the gut to the liver by SLC35F2 . There, QNG1 cleaves Q to release the q base, which enters the serum for wider distribution.' The Cancer Connection Paris said that SLC35F2 was characterized as an oncogene in previous research and is known to contribute to the progression of various cancers through its overexpression, including non-small cell lung cancer, papillary thyroid cancer, and bladder cancer. Paris added that SLC35F2 's role in Q and q transport provides a significant mechanistic explanation for its oncogenic activity. 'High SLC35F2 expression is an unfavorable prognostic factor for patient survival in multiple cancers. SLC35F2 overexpression increases cellular Q/q levels, promoting higher Q34 modification of tRNAs. Consequently, Q modification may offer malignant cells a selective advantage through codon-biased translation,' he said. Additionally, the study identified SLC35F2 (or its homologs) as the unique Q/q transporter in the yeast Schizosaccharomyces pombe and the human parasite Trypanosoma brucei , Paris said. 'While the physiological importance of Q-tRNA varies by species — for example, loss of Qtp1 does not affect growth in S pombe or T brucei — this comparative analysis strengthens the evidence for SLC35F2 's role in humans and reveals its conserved function in eukaryotes that salvage Q and q.' He said, 'In essence, the study provides the missing link in the queuine salvage pathway, significantly advancing our understanding of how this essential micronutrient is acquired, distributed, and regulated, and its profound impact on health and disease, particularly in the context of cancer.'
The Guardian
05-06-2025
- Health
- The Guardian
Nine ways to avoid food poisoning: microbiologists' tips for safe, healthy eating
Do you use the same kitchen sponge for days on end? Let your takeout pizza languish on the counter overnight? We all have questionable kitchen habits – but when it comes to food safety, shortcuts we think of as harmless can open the door to dangerous pathogens such as bacteria and toxins, according to microbiologists. Here's how experts suggest staying safer in the kitchen. 'Home cooks tend to underestimate how cross contamination can spread bacteria across the kitchen,' says Dr Siyun Wang, professor of food safety engineering at the University of British Columbia. E coli, salmonella and listeria can easily transfer from raw produce, meat and eggs to other points we touch, such as a refrigerator or faucet handle, where Wang's research has shown they may be able to linger for weeks. To avoid cross-contamination when cooking, wash your hands frequently and well – for 20 seconds under warm water, then dry them on a clean towel reserved especially for that purpose. Do not rinse raw meat, such as chicken, she says. Doing so may help spread harmful bacteria, including via tiny airborne water droplets. Sanitize surfaces: Dr Jae-Hyuk Yu, a professor of bacteriology at the University of Wisconsin-Madison, recommends using a bleach solution (one tablespoon of bleach per gallon of water), an Environmental Protection Agency-registered kitchen disinfectant, or an alcohol-based spray for sanitizing hard surfaces, especially after preparing raw meat. And when handling cleaning chemicals, use gloves and ventilate well. He recommends cleaning fridge shelves monthly and ensuring your fridge is consistently under 40F to prevent bacteria from lurking around. Cook meat thoroughly: Always cook meat to its proper internal temperature, per the United States Department of Agriculture's guidelines: 145F for whole cuts of beef, pork, lamb, veal and fish (with a three-minute rest for meat), 160F for ground meats, and 165F for all poultry. Yu uses plastic cutting boards, rather than wood, for meat. 'Even clean boards can harbor microbes in grooves,' he says, so wash any kind of board well with hot water and antibacterial soap after use. 'Sponges are notorious bacterial reservoirs,' says Yu. 'Cleaning a knife used on raw chicken with a sponge, then using that same sponge on other dishes, can absolutely spread dangerous pathogens.' If you must use a sponge, microwave it, wet, for one to two minutes once a day or run it through the dishwasher with a heat-dry cycle, he advises. Yu replaces kitchen sponges every one to two weeks, and personally prefers sanitizable dishcloths that can be changed daily and put through a hot laundry cycle. While it is convenient to thaw frozen meat at room temperature, doing so 'allows the outer layers to enter the 'danger zone' between 40F and 140F, where bacteria can multiply rapidly, long before the center is thawed,' says Yu. Instead, thaw meat in the refrigerator. If you want to cook the meat immediately, use the microwave or place it in a sealed bag and submerge it in cold water, changing the water every 30 minutes. These methods keep the temperature in a safe range and limit bacterial growth. Leaving food out at room temperature is 'essentially incubating the bacteria that are in that food', says an Idaho-based microbiologist and medical laboratory scientist certified by the American Society for Clinical Pathology who goes by the pseudonym Morticia to avoid harassment as she shares food science information online. This gives them time to produce enterotoxins that can lead to symptoms like vomiting. 'A lot of these toxins are heat stable,' she says. Reheating them may get rid of bacteria, 'but the toxins will still make you sick'. Morticia recommends being especially careful with starchy leftovers like rice and pasta, where Bacillus cereus, a nasty foodborne pathogen, can start to grow within hours if left out. If you're saving food for later, refrigerate it within two hours. If you're actively eating over time – say, at an indoor party – food can stay out for up to four hours. But in hot outdoor settings such as a barbecue, that window shortens, she explains. The Food and Drug Administration and USDA recommend keeping refrigerated leftovers no longer than three to four days. 'If you freeze food, it will stay safe to eat for a very long time,' Morticia says. 'Respecting these dates is one of the best ways of avoiding potential health problems,' says Dr Alvaro San Millan, an expert in bacteria at the National Center for Biotechnology in Madrid. Some foods, such as packaged snacks, may be fine to eat days or weeks after their best before date has passed, particularly if they're unopened or have been properly stored. But it's not always easy to tell if something has gone bad. 'If food smells or tastes funny, that's definitely a red flag,' says San Millan. But pathogens can accumulate without alerting our senses to trouble. 'Certain bacteria, such as salmonella, can produce infections in humans even if they are at a very low concentration in the food – so low that you could never appreciate any change in a sniff or taste test,' says San Millan. Most of the time, eating questionable food will probably only lead to some gastrointestinal discomfort, but 'if you are unlucky and get infected by bacteria such as Listeria or Salmonella, or intoxicated with botulinum toxin, you may be in serious trouble,' he says. Sign up to Well Actually Practical advice, expert insights and answers to your questions about how to live a good life after newsletter promotion Can you just get rid of the visible mold on cheese and eat the rest? 'It depends on the type of cheese,' says Wang. If you spot mold on soft cheese, such as cottage and cream cheese, 'the entire product should be discarded'. Mold can send microscopic threads throughout the cheese, contaminating more than what is visible on the surface. 'For hard cheese such as cheddar, you can cut off at least 1in around and below the mold spot and keep using it,' Wang says, because fungi aren't able to spread as quickly through denser textures. 'The knife should be kept away from the moldy part to avoid cross contamination,' she says. People have used food preservation techniques like salting and pickling for millennia. But simply adding preservative ingredients to a dish doesn't 'shield' it from bacteria. Spicy, salty or acidic elements might slow spoilage under specific conditions, as with jerky or sauerkraut, but don't guarantee protection from harmful pathogens. There have been listeria and salmonella outbreaks from pickles, for instance, notes Morticia. 'There isn't much of a difference in regard to bacterial contamination and pathogen transmission' when it comes to organic and conventional produce, Morticia says. However, when buying local, 'the supply chain is a lot shorter and fewer people are coming into contact with that food,' she says. This means 'you are at a lower risk of transmission of some pathogens,' she says. Unfortunately, individual consumers don't have total control over food safety – systemic factors have a significant impact on the quality of what we eat. The FDA has faced significant reductions in funding and staff, which 'could lead to gaps in inspection and monitoring', says Yu. Reports suggest that spending freezes are already limiting food safety inspectors' ability to travel to farms or acquire food samples for testing. For individuals at home, less regulatory oversight means higher stakes decisions at the grocery store. Common food categories such as meat, eggs, shellfish, sprouts, greens and seeded vegetables such as tomatoes and cucumbers are all relatively high-risk for contamination. 'Now is a good time for consumers to be more cautious,' says Yu, particularly with 'high-risk foods like leafy greens, especially bagged lettuce,' which is prone to contamination with pathogens such as salmonella, listeria and E coli because of the way the greens are mixed from different farms and mass-processed before packaging. Morticia has changed her eating habits to prioritize safety in light of weaker industry regulations. 'I went vegan in January, because most foodborne pathogens are zoonotic in origin, meaning they come from cows and pigs and chickens,' she says. She's also opting for more stir-fries and fewer salads. 'Cooking all of my foods significantly lowers risk,' she says.
